Technologies for economic and functional lightweight design

Table of Contents

1. Frontmatter

2. Innovative and Smart Production

   1. Frontmatter

   2. Life Cycle Assessment of Thermoplastic Hybrid Structures with Hollow Profiles

      Alexander Liebsch, Michael Müller-Pabel, Robert Kupfer, Maik Gude

      Abstract

      The combination of innovative materials, process chins and intelligent material-adapted design concepts enables an efficient part production for future mobility applications. Hybrid structures made of thermoplastic pre-impregnated composite (TPC) sheets and injection moulding bulk material have already crossed the threshold to series production. Thanks to a newly developed production technology, hollow profiles with continuous fibres can now also be integrated into thermoplastic composite hybrid structures in the sense of a modular design system. However, the resource consumption of such hybrid structures has not yet been investigated.

      This contribution describes the set-up and life cycle analysis (LCA) of a highly automated manufacturing process for the production of complex crash-loaded vehicle structures in thermoplastic composite design. The concept bases on the production of a hollow profile made of hybrid yarn, which is subsequently overmoulded and combined with a TPC sheet in an injection moulding process. For the hollow profile manufacturing, a novel automated preforming technology is used. The textile preform is then consolidated in a variothermal consolidation station, consisting of a temperature control system and an additively manufactured consolidation tool. For the subsequent overmoulding of the hollow profile, methods for stabilising the hollow profile were studied and implemented in an injection moulding complex. A plasma system for activating the surface of the hollow profile was used to create a permanent joint between the hollow profile and TPC sheet. At the example of a backrest with an integrated seat belt, the technology and its potential application in crash-relevant structures was proven.

      In addition to the process set-up, manufacturing studies were carried out with the aim of evaluating the ecological potential of the process chain. For this purpose, a cradle-to-gate approach was chosen, in which the process-related energy consumption as well as the material consumption were measured and used for LCA. Thus, the most relevant process steps can be identified and possibilities for increasing efficiency can be derived.

   3. Interdisciplinary Research for the Development and Realization of a Structural Component in Multi-Material Design Suitable for Mass Scale Production

      Benjamin Bader, Werner Berlin, Michael Demes

      Abstract

      Lightweight design offers a reduction of local emissions and increase the range and handling dynamic of automobiles while driving. With a 40% share of the total vehicle mass, the body-in-white, consisting of high-strength steel materials, is a significant lever for weight reduction, but it is reaching its limits as the sheet thickness is further reduced, especially in crash-relevant structures such as A- or B-pillars, bumper cross beams e.g. (Friedrich in Leichtbau in der Fahrzeugtechnik, Springer, ATZ/MTZ-Fachbuch. Wiesbaden, 2017; Liu et al. in Int. J. Adv. Manuf. Technol. 69:211–223, 2013). An alternative approach are hybrid structures made of a combination of fibre-reinforced plastics (FRP) and metal sheets. The standard metal components can be improved by the targeted use of FRP in many ways. It enables a production of completely new components with increased performance and higher level on functional integration. This paper describes the transition of a lower A-pillar of a high-volume segment vehicle by showing the changeover from the monolithic steel design to the hybrid plastic-metal design. Therefore, the conceptual design of the component and its production are explained.

   4. Net Shape Stacking and Consolidation of Thermoplastic Composite Tapes

      Paul Zwicklhuber, Norbert Müller

      Abstract

      Thermoplastic composite tapes are produced with a specific width, e.g. 300 or 600 mm. A common production method is first to slice the tape rolls into narrow tapes bands with a width of e.g. 50 mm. These narrow tapes are used for stacking operations. Upon using such a technology, it is necessary to combine several narrow tapes to end up with a single layer. The outer edges of the tape stack normally extrude beyond of the area needed for the part, meaning, a cutting operation is necessary, either right after the stacking or after the consolidation. A beneficial alternative approach starts with large cutouts from the rolls, which are obtained by efficient stamping. These cutouts cover as much area as possible in one piece. The idea is to use the full tape width, if possible. The cutouts are stored in automatized magazines and become stacked efficiently employing a pick-&-place approach. The use of image processing enables precise adjustment of the gaps and overlaps.

      This net-shape stacking technology leads to stacks that consist of a minimum number of tape cutouts. Even different types of tapes can be combined. The net-shape stacking is followed by an also net-shape consolidation in a heating-&-cooling unit. Both, the stacking unit as well as the consolidation unit are capable producing stacks and blanks within a typical injection moulding cycle time of one minute. The consolidated blanks fulfil the requirement of a best fit outer contour, which can be draped into the desired shape of the final part. Furthermore, the tailored composite blanks may expose the distinct variations in thickness and fibre orientation, which is optimized for the final part’s specific loading conditions.

   5. Thermoset Technologies for Cost Efficient Production of Lightweight Composites

      Lars Moser, Sigrid Heide, Ian Swentek, Uwe Schmidt, Manuel Seiz

      Abstract

      The automotive industry is evolving rapidly with increasingly rigorous emission targets and leaps toward electrification and autonomous driving. These forces continue to trigger lightweight solutions, advancing the adoption of novel composite materials for diverse applications. Composite materials have been used for body parts in sports and luxury vehicles for a long time, enabling design freedom, astonishing aesthetics and leading-edge driving performance. This extended abstract discusses state of the art composite manufacturing processes enabling cost-efficient high-quality parts production.

3. Factories of the Future

   1. Frontmatter

   2. Contribution to Digital Linked Development, Manufacturing and Quality Assurance Processes for Metal-Composite Lightweight Structures

      Daniel R. Haider, Fabian Folprecht, Johannes Gerritzen, Michael Krahl, Sebastian Spitzer, Andreas Hornig, Albert Langkamp, Maik Gude

      Abstract

      More and more effort in development processes is required to meet the constantly increasing demands on technical components. Especially in hybrid structures, the high number of degrees of freedom in development due to the different material properties and interactions between them leads to complex and multi-disciplinary processes. Digitalisation is one option to meet the increasing demands for shorter development times and more efficient products. In addition, hybrid structures require a generally applicable procedure and guidelines for the design and preliminary dimensioning to support the engineering. A novel approach is presented to digitally link the development steps to create an interactive development process and a structure for a holistic data analysis. This is exemplary shown for an open, ribbed profile made of hybrid metal-composites in a module-based scheme. For a pre-dimensioning solution of the cross-section profile, analytical models, linked to adaptable numerical models, have been build up and transferred in the process model. Moreover, experimental validation concepts for the bending properties of a car body component is presented.

   3. Thinking Innovation Ahead – Joint Semantic Modelling for Integrated Product and Production at the Research Campus Arena2036

      Clemens Ackermann, Manuel Fechter, Peter Froeschle

      Abstract

      The goal of the Research Campus ARENA2036 is, based on excellent, interdisciplinary basic and applied research, to produce potentially disruptive and leap-frog innovations, to transfer them to industry, and thus to contribute to the active shaping of work, mobility, production of the future, and digitization. The seamless transfer of research results into industrial application is intended to increase the competitiveness of the business location Baden-Württemberg and to enable the creation of novel business models – especially for SMEs. An essential component here is the interdisciplinary and trans-institutional approach of various fields of science and application, which is reflected in the close cooperation of all actors under the umbrella of ARENA2036. Based on this basic idea, current research work is carried out in the field of data interoperability in the domains of product development, and production system design. The goal is to achieve a significant overall reduction of product development and market introduction times. This topic is particularly significant due to the currently ongoing transformation processes in the automotive industry, which question the prevailing product and production patterns and require an increasing flexibility of manufacturing processes. New product and production technologies have to be incorporated into serial production at ever shorter intervals, which poses great challenges for both product design and corresponding production systems.

      This paper conceptually approaches the basic ideas in innovation design incorporated at the Research Campus ARENA2036 as a research platform that allows for joint research in a precompetitive environment thus enabling all partners to think innovation ahead. One example for this, is the holistic semantic modelling of integrated product and production development in the research projects Fluid Production and Digital Fingerprint. Both projects conceive an approach to production that emphasizes the need for constant flexibility qua anthropocentric reconfigurability.

   4. Integrated Factory Modelling – Enabling Dynamic Changes for the Factory of the Future at the Example of E.GO Mobile AG

      Peter Burggräf, Matthias Dannapfel, Sebastian Patrick Vierschilling

      Abstract

      Fast-moving changes in products, materials and process technologies require factory planning processes and procedures to be flexible and dynamic. Today, most factory planning projects are missing their budget (72%) and time targets (60%). To reduce these deviations, digitalization is key to success, but in current approaches, coordination between different planning disciplines is missing as well as different technology maturity levels prohibit automated interfaces. The Integrated Factory Modelling (IFM2) is an interdisciplinary planning approach for Green- and Brownfield factories coordinating all planning disciplines from infrastructure to process planning across the factory lifecycle. Therefore, the Integrated Factory Model (IFM) as a single dataset is established for all planning participants, accessible everywhere and on every device. Collaboration is enhanced by the working mode with an agile factory scrum process. Based on the IFM user-specific smart expert tools have been developed supporting planners and managers.

      As a result, planning processes could be improved significantly, reducing costs by 20–30%, saving one-year planning time for a Greenfield and reduce planning failures significantly. IFM was initially applied and introduced to the e.GO Mobile AG, which is used as an example showing real-life use cases, challenges as well as next development steps.

4. Life-Cycle Engineering

   1. Frontmatter

   2. Methodology for Assessing the Environmental Impact of Emerging Materials

      Malte Schäfer, Martina Gottschling, Felipe Cerdas, Christoph Herrmann

      Abstract

      In order to reduce environmental impacts of product systems through material research and development, to identify mitigation potential, and to avoid problem shifting, information about the environmental impact of emerging materials is needed at an early stage. This information can support decisions on material selection as well as manufacturing process optimization. The goal is to reduce the impact of an emerging material so that it is lower than the impact of an established material. We propose a methodology to address this need. It consists of four steps: 1) reference LCA, 2) forecast LCA of emerging material, 3) scaling and 4) comparison. We apply the methodology to automotive seat cover materials such as bovine leather, faux leather and a fictitious flax-based material, where the production of the latter shares some production steps with leather. The results indicate how much environmental space the to-be-developed manufacturing process of the fictitious material can take up before it surpasses that of leather and faux leather. This way, the methodology can support the material research and development process in identifying and creating alternative materials with a lower environmental impact.

   3. Systematic Design of Body Concepts Regarding Mini-Mal Environmental Impacts in an Early Concept Phase

      Lars Reimer, Pavan Krishna Jois, Hartmut Henkelmann, Jens Meschke, Thomas Vietor, Christoph Herrmann

      Abstract

      For internal combustion engine vehicles, the use stage dominates the life cycle emissions. In comparison, the life cycle emissions of battery electric vehicles highly depend on the electricity mix. With consideration of an European electricity mix the life cycle emissions split approximately equally between the production and use stage. Approximately 46% of these emissions is caused by the battery production. But the absolute and relative share of emissions from the vehicle production increase as well. Thus both stages have to be considered for the environmental assessment of body parts. Therefore the environmental impact of different material concepts as well as production and joining technologies are in focus of the development. A decision regarding environmentally optimized body concepts has to be made in the concept phase. A first approach provides mass indices from Ashby 1999. So, concepts made out of different materials can be developed in a given design space. These concepts are evaluated using a simplified life cycle assessment, which considers different body designs, mobility concepts and markets (electricity mixes). It can be shown that there is a large variance of greenhouse gas emissions for a given lightweight design potential. Hence, an optimization procedure to find concepts with the lowest environmental impacts is needed. In this paper a first approach for an optimization procedure concerning ecological aspects of body parts is described and demonstrated with an example application.

   4. Processing Capabilities for Thermoplastic Composites – Minimum Material Consumption and Recyclability

      Norbert Müller, Philipp Seinsche

      ABSTRACT

      An important measure for improved lightweight performance is utilisation of materials only to the extent, as it is necessary for the application. To achieve a minimum part weight in high volume lightweight applications, it is necessary to combine thermoplastic composite sheet materials exposing different thicknesses. Then, a minimum material consumption is gained. Such composite components have the capabilities of being fully recyclable. Used parts as well as scrap and cut-off that arises during production can be recycled and used for injection moulding of ribs and other geometry, even to become part of the same composite component later on. However, there are considerable challenges in the processing since different composite sheets need to be processed simultaneously. A processing unit was designed, build and tested that is capable to process thermoplastic composite sheets with three different thicknesses. The resultant part, a structural automotive door component, exposes areas were the composite sheet thickness is 0.6 mm, 1.0 mm, and 2.5 mm, respectively. Besides of the injection moulding, the processing requires two different kind of infrared ovens with a specialized software for the control of the heating and three articulated robots for the automated handling operations of the composite blanks.

5. Generative Manufacturing

   1. Frontmatter

   2. Evaluation of Technologies for the Fabrication of Continuous Fiber Reinforced Thermoplastic Parts by Fused Layer Modeling

      Daniel Pezold, T. Rosnitschek, A. Kleuderlein, F. Döpper, B. Alber-Laukant

      Abstract

      In this research technologies for the production of continuous fiber-reinforced thermoplastics using additive manufacturing are investigated and evaluated. The focus is on the “Fused Layer Modeling” (FLM) process, which is based on an additive, thermoplastic extrusion process. The possibility of combining the plastic filament with continuous fibers allows a specific fiber reinforcement to be introduced into the part to increase the mechanical properties. First, an overview of the technologies for processing continuous fibers is presented. These strategies differ in the design of the machine (hardware) and the possibilities for the constructive insertion of the continuous fibers in slicing (software). The differences of the technologies are the processing method of the fiber as well as the fiber roving used in the extrusion process. The maximal fiber volume content and the interlaminar fiber-matrix adhesion are investigated in various commercial technologies by means of tensile and bending tests. In conclusion, the different technologies are evaluated with regarding the maximal fiber volume content and quality of interlaminar fiber-matrix adhesion.

   3. Design of Additively Manufactured Heat-Generating Structures

      Karl Hilbig, Hagen Watschke, Thomas Vietor

      Abstract

      Multi-material additive manufacturing provides new design freedom for integration of functions and opens new possibilities in innovative product design due to local material variations. In particular, material extrusion (MEX) allows for combination of different industrial-grade thermoplastic materials to enhance the functionality of a product by integration of functions. Thus, for instance, electrically conductive structures or heat-generating surfaces can be incorporated in a part by using conductive polymers filled by carbon black (CB), carbon nanotubes (CNT) or copper nanowires (CNW).

      The resultant properties of additively manufactured parts are mainly influenced by the choice of process parameters. In addition to mechanical properties (e.g. stiffness and strength), electrical properties are also like resistivity and volumetric power density influenced. In order to design heat-generating structures in a targeted manner, the dependencies between process parameters and electrical performance must be determined. Thus, in this article the dependencies between the process parameters extrusion temperature, raster angle orientation and extrusion speed are investigated experimentally. In order to adjust the resistivity of an additively manufactured part and surface temperature by resistive heating, these dependencies are transferred into mathematical descriptions. The setup of design of experiment is based on model selection for analytical description of material-specific characterization.

      In order to demonstrate the potential of additively manufactured heating structures by material extrusion a garnish mold with incorporated heating panels is built as multi-material design. Finally, the heating of the prototypical panel is analyzed by thermographic analyses. Thus, the approach for achieving certain surface temperatures by varying process parameters and part geometry based on the mathematical description is validated.

   4. Process Simulation for Screw Extrusion Additive Manufacturing of Plastic Parts

      Johannes Albers, Ulf Hillemann, Andreas Retzlaff, André Hürkamp, Klaus Dröder

      Abstract

      Additive manufacturing of plastic parts is a widely spread production method for prototyping. In the recent past, additionally series applications evolved from different sectors of industry. Especially plasticizing processes are characterised by high printing speed and a broad range of materials which can be provided both as filament and granulate. The latter offers the advantage of lower material costs compared to filaments but requires a screw extruder to plasticise and homogenise the plastic melt prior to its deposition through a nozzle. Screw extruders have a wide processing range and therefore are capable of producing a huge variety of printing bead shapes. This shape is directly affected by several extrusion settings and has a great impact on manufacturing time as well as mechanical properties and surface quality of fabricated parts. It would take great effort to determine the influence of process parameters like temperatures and velocities in experimental trials.

      In this contribution a process simulation is presented which predicts the bead shape for screw extrusion additive manufacturing. A computation of material flow is performed including nozzle outlet and bead shaping in the gap between nozzle and printing platform. The free surface of the plastic melt is tracked using a volume of fluid method. Numerical investigations follow the concept of Design of Experiments in order to identify significant relationships between extrusion settings and bead shape. By this means, processing windows can be estimated virtually and conclusions can be drawn regarding slicing parameters and manufacturing time.

6. Bio-based Innovations

   1. Frontmatter

   2. Biomimetic Soft Robotic Peristaltic Pumping System for Coolant Liquid Transport

      Falk J. Tauber, Tom Masselter, Thomas Speck

      Abstract

      In nature and technology, liquids are transported and distributed in a directed manner via pumping systems. Technical pumps often show signs of wear due to abrasion on moving parts, erosion and liquid contamination, which can lead to damage and unwanted noise. Innovative pump systems for electro mobility applications should have particularly low noise emission. In the course of evolution, various solutions have emerged in nature and can serve as a source of inspiration for the development of biomimetic pumping systems. In the last decade, the development of various biomimetic peristaltic systems highlight this pronounced biomimetic potential. These systems are based on principles behind bowel and esophageal peristalsis and incorporated within soft robots and medical devices. The main goal of this study was the biomimetic implementation of peristalsis into a flexible, silent, robust, energy efficient, space-saving and low cost technical application for the usage in combustion engines, electric engines and cooling systems. The biomimetic pump of the present study is based on the esophageal peristalsis and enables an easy, quiet and safe transport of a variety of Newtonian and non-Newtonian fluids with variable viscosities. The characterization of individual actuators as well as the entire peristaltic pump system in terms of closing rate and volume flow proved the influence of the actuator frequency and different peristaltic actuation patterns on the generated flow rate. The results show that the biomimetic flexible and elastic self-priming peristaltic pump based on silicone achieves sufficient flow rates of more than 250 l/h and thus offers an excellent alternative to conventional technical pumps in the field of electro mobility.

   3. Biomimetic Suction Cups for Energy-Efficient Industrial Applications

      Harald Kuolt, Tim Kampowski, Simon Poppinga, Thomas Speck, Ralf Tautenhahn, Atena Moosavi, Jürgen Weber, Felix Gabriel, Erika Pierri, Klaus Dröder

      Abstract

      Suctions cups are widely used in industrial applications for handling various goods. In the animal kingdom, a multitude of analogous structures has evolved, e.g. in octopuses and leeches, which allow the respective organisms to securely attach and detach from various substrates. To date, the biological suction cups outperform their technical counterparts in terms of versatility, as they allow attachment also on challenging (e.g. porous, wet and fouled) surfaces.

   4. Bio-Sourced Artificial Leather for Interior Automotive Applications

      Stefan Friebel, Steffen Sydow

      Abstract

      Flexible interior artificial leather is today produced on the basis of soft PVC and PUR and to a small extent of polyolefins, whereby the polyurethanes are primarily suitable for high-quality materials.

      PU-based coating systems have several advantages: The mechanical properties of the coating can be adjusted in a wide range and they are thermally stable. Furthermore, they are considered as a substitute for PVC because they are free from plasticizers.

      Fraunhofer WKI has developed a series of bio-sourced polyurethane leathers with a bio-sourced proportion of >85 wt.-%. The polymer matrix consists of sugar and vegetable oil derivatives and it is waterborne. The polymer material is UV-curable, providing an improved mechanical performance for the leather as well as an excellent chemical resistance. The elongation at break could be up to 175%, while the bio-source artificial leather is resistant to water and common household chemicals, such as red wine, 48% alcohol, mustard and water. For applications where there is no requirement for highly flexible materials e.g. dashboard lamination or gear stick, we also developed a finish that is resistant to sunscreen. Furthermore, a flexible head rest was designed by memory-wood foam. The final properties of the wood foam are accomplished by a combination of wood and a bio-soured latex to reach a pliable head rest. After the construction of head rest, the material was covered with the bio-sourced polyurethane leather smoothing the surface of the memory-wood foam.